a) Field of the Invention
The present invention relates to a direct current (DC) motor, and more particularly to a DC motor which is controlled by an integrated circuit (IC).
b) Description of the Related Art
A spindle motor, one of various types of DC motors, has a housing including a stator, and a rotor rotatably supported on the housing and facing the stator.
In a brushless DC motor, permanent magnets are mounted on the rotor, and armature coils are mounted on the stator. Controlled DC current is supplied to the armature coils of the stator to rotate the rotor. In order to control the current flowing through the armature coils while monitoring the rotation of the rotor, a control IC is generally used. The control IC is mounted on and connected to an IC circuit board. The IC circuit board and the motor are interconnected by wirings such as flexible printed circuit board. This IC circuit board is also connected to an external power source and control circuit.
In a known structure of a DC motor, the housing is formed with a through hole at the central area thereof. Grooves are formed in the side wall of the through hole to mount armature coils within the grooves. The rotor has a shaft formed at the central area thereof. The rotor shaft is supported within the through hole of the housing by means of bearings. Permanent magnets are mounted on the rotor at its outer circular wall which is rotatably housed within a space formed in the groove.